1. Field
The inventive concept relates to an apparatus that determines whether the apparatus should access a joint test action group (JTAG) device, and more particularly, to an apparatus including a JTAG authentication device which is capable of performing authentication using a JTAG access circuit without correcting a JTAG controller mounted in the apparatus, and a method of authenticating the JTAG-compliant device using the apparatus.
2. Description of Related Art
A JTAG-compliant device can be used as a debugger when designing an embedded system. The JTAG-compliant device can check data stored in a memory of a device, and/or check input/output data, and/or check the states of functional blocks which are to be debugged, via a test access port (TAP) installed in the device. However, the JTAG-compliant device may also be used to extract important data of the device, sometimes which for illicit or malicious purposes.
In addition, there is trouble when a TAP controller is corrected in order to overcome the abovementioned problems. For example, in the case of a device that uses a core such as Advanced RISC Machines (ARM), a designer of the device may consider correcting inner circuits of the core. However, correcting such circuits is risky. Moreover, if there is no authority to correct the core, correction may not be possible.
Accordingly, a new authentication circuit needs to be added while obviating the need to correct the circuits.